1. Field of the Invention
The invention relates to a paint-spraying apparatus for producing a shaped paint jet, and to a needle for a needle valve for a paint-spraying apparatus.
In accordance with the invention, the paint-spraying apparatus can also be used for other air-driven application methods which make use of the function according to the invention of the rotatable production of a shaped paint jet of the paint-spraying apparatus.
2. Description of Related Art
In the field of spraying application methods, for example in the case of paint spraying or lacquer spraying, there are a large number of basic technical principles. Besides what are known as airless methods, which atomize paint at high pressure and apply it to a surface, there are a large number of methods operated on the basis of compressed air. Here, a paint jet exiting from a nozzle is nebulized by means of air masses (primary atomization air) flowing past and is thus transported in the form of a paint jet mist in the direction of a working plane. The working plane arranged at a suitable working distance for a coating procedure is contacted in this way by the paint jet, and the paint is thus applied thereto. In this case, apparatuses operated on the basis of compressor compressed air and also what are known as HVLP (high volume low pressure) apparatuses inter alia are known from the prior art and differ in terms of some operating parameters, for example the nozzle air pressure, from the conventional high-pressure apparatuses.
The type of apparatus from the prior art is suitable for providing a flat paint jet, which provides advantages when applying a paint to a surface. Compared to a radially symmetrical round paint jet, a flat jet provides increased homogeneity as the paint is applied, similarly to application by means of brush or application by means of roller, whereby the result of the paint coating is considerably improved.
Paint-spraying devices, in which a radially symmetrical round paint jet, which exits from a paint nozzle, is deformed by air deflection means which are arranged to the side of the paint nozzle and are designed in the form of what are known as air horns, such that a produced flat paint jet appears in the region of a working plane, are known from the prior art, for example from EP 0 596 939 B1.
Furthermore, a spray head for producing a flat paint jet on a paint-spraying apparatus is known from DE 10 2009 053 449 A1, with which wall paint or viscous paint can also be processed well. Depending on the design of the spray head, the flat jet that can be produced has a vertical or horizontal alignment, such that it is either suitable for applying the paint optimally to vertical or horizontal wall faces. A flat paint jet in horizontal and vertical direction is used above all to allow the user to coat the surfaces vertically and horizontally in the two primary working directions (=gun movement). This is important in particular in order to carry out what is known as cross-coating, in which a surface is coated successively once in a vertical working direction and once in a horizontal working direction in order to avoid structural shadowing.